U.S. patent number 4,494,828 [Application Number 06/366,673] was granted by the patent office on 1985-01-22 for zoom lens system of relatively high zoom ratio ranging to wide angle photography.
This patent grant is currently assigned to Minolta Camera Kabushiki Kaisha. Invention is credited to Hisayuki Masumoto, Shuji Ogino.
United States Patent |
4,494,828 |
Masumoto , et al. |
January 22, 1985 |
**Please see images for:
( Certificate of Correction ) ** |
Zoom lens system of relatively high zoom ratio ranging to wide
angle photography
Abstract
A zoom lens system of a relatively high zoom ratio ranging from
a telephoto to a wide field angle is provided. The zoom lens system
comprises from the object to the image side a first lens group of a
positive refractive power, a second lens group of a negative
refractive power consisting of a first negative subgroup, a second
positive subgroup located on the image side of the first negative
subgroup with an air space and a third negative subgroup located on
the image side of the second positive subgroup with an air space,
and a third lens group of a positive refractive power, wherein at
least the air space between the first and second lens groups and
the air space between the second and third lens groups are
changeable upon zooming. The focusing can be practiced by moving
the first lens group with the other lens groups left
stationary.
Inventors: |
Masumoto; Hisayuki (Sakai,
JP), Ogino; Shuji (Osaka, JP) |
Assignee: |
Minolta Camera Kabushiki Kaisha
(Osaka, JP)
|
Family
ID: |
27279267 |
Appl.
No.: |
06/366,673 |
Filed: |
April 8, 1982 |
Foreign Application Priority Data
|
|
|
|
|
Apr 9, 1981 [JP] |
|
|
56-53948 |
Apr 10, 1981 [JP] |
|
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56-54672 |
Jan 26, 1982 [JP] |
|
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57-11090 |
|
Current U.S.
Class: |
359/690;
359/685 |
Current CPC
Class: |
G02B
15/143105 (20190801) |
Current International
Class: |
G02B
15/163 (20060101); G02B 15/173 (20060101); G02B
007/04 () |
Field of
Search: |
;350/423,427,428 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Corbin; John K.
Assistant Examiner: Dzierzynski; Paul M.
Attorney, Agent or Firm: Jackson, Jones & Price
Claims
What is claimed is:
1. A zoom lens system of a relatively high zoom ratio ranging to
wideangle photography in which the shortest focal length is less
than the length of the diagonal line of the effective image plane,
comprising from the object to the image side:
a first lens group of a positive refractive power;
a second lens group of a negative refractive power consisting of a
first negative subunit, including at least two separate negative
lenses, a second positive subunit located on the image side of the
first negative subunit with an unchangeable air space and a third
negative subunit located on the image side of the second positive
subunit with an unchangeable air space; and
a third lens group of a positive refractive power, wherein at least
an air space between the first and second lens groups and an air
space between the second and third lens groups are changeable upon
zooming.
2. The invention of claim 1, wherein at least one of the two
separate negative lenses is a doublet.
3. The invention of claim 1, wherein the absolute value of radius
of curvature is less on the image side surface than on the object
side surface with respect to the object side one of the two
separate negative lenses.
4. The invention of claim 1, wherein the second positive subunit
includes at least one positive lens with an object side surface of
a lesser absolute value of radius of curvature and an image side
surface of a greater absolute value of radius of curvature.
5. The invention of claim 4, wherein the positive lens in the
second positive subunit is a doublet.
6. The invention of claim 1, wherein the third negative subunit
includes at least one negative lens with an object side surface of
a lesser absolute value of radius of curvature and an image side
surface of a greater absolute value of radius of curvature.
7. The invention of claim 6, wherein the negative lens in the third
negative subunit is a doublet.
8. A zoom lens system of a relatively high zoom ratio ranging to
wide angle photography in which the shortest focal length is less
than the length of the diagonal line of the effective image plane,
comprising from the object to the image side:
a first lens group of a positive refractive power;
a second lens group of a negative refractive power consisting of a
first negative subunit including at least two separate negative
lenses, a second positive subunit located on the image side of the
first negative subunit with an unchangeable air space and a third
negative subunit located on the image side of the second positive
subunit with an unchangeable air space; and
a third lens group of a positive refractive power, wherein at least
an air space between the first and second lens groups and an air
space between the second and third lens groups are changeable upon
zooming, wherein the whole first lens group is movable for focusing
with the other lens groups left stationary.
9. A zoom lens system of a relatively high zoom ratio ranging to
wide angle photography in which the shortest focal length is less
than the length of the diagonal line of the effective image plane
comprising from the object side to the image side:
a first lens group of a positive refractive power;
a second lens group of a negative refractive power consisting of a
first negative subunit including at least two separate negative
lenses, a second positive subunit located on the image side of the
first negative subunit with an unchangeable air space and a third
negative subunit located on the image side of the second positive
subunit with an unchangeable air space; and
a third lens group of a positive refractive power wherein at least
an air space between the first and second lens groups and an air
space between the second and third lens groups are changeable upon
zooming, wherein the first and third lens groups are movable upon
zooming.
10. The invention of claim 9, wherein the second lens group is left
stationary upon zooming.
11. The invention of claims 1 or 8 or 9, wherein the third lens
group is divided into two subunits, an air space between the two
subunits being further changeable upon zooming.
12. A zoom lens system of a relatively high zoom ratio ranging to
wide angle photography in which the shortest focal length is less
than the length of the diagonal lines of the effective image plane,
comprising from the object to the image side:
a first lens group of a positive refractive power;
a second lens group of a negative refractive power consisting of a
first negative subunit including at least two separate negative
lenses, a second positive subunit located on the image side of the
first negative subunit with an unchangeable air space and a third
negative subunit located on the image side of the second positive
subunit with an unchangeable air space; and
a third lens group of a positive refractive power, wherein at least
an air space beween the first and second lens groups and an air
space between the second and third lens groups are changeable upon
zooming, wherein the lens system fulfills the following
conditions:
wherein:
R.sub.a represents the radius of curvature of the most image side
surface of the first negative subunit, and
R.sub.b represents the radius of curvature of the most object side
surface of the second positive subunit.
13. The invention of claim 12, wherein the lens system further
fulfills the following condition:
wherein .PHI. represents the refractive power of the air lens
formed between the second and positive subunit and the third
negative subunit.
14. The invention of claim 12, wherein the lens system further
fulfills the following condition:
wherein: f.sub.I II represents the total focal length of the first
and second lens groups at the shortest focal length of the whole
lens system and f.sub.w represents the shortest focal length of the
whole lens system.
15. A zoom lens system of a relatively high zoom ratio ranging to
wide angle photography in which the shortest focal length is less
than the length of the diagonal line of the effective image plane,
comprising from the object to the image side:
a first lens group of a positive refractive power;
a second lens group of a negative refractive power consisting of a
first negative subunit including at least two separate negative
lenses, a second positive subunit located on the image side of the
first negative subunit with an air space and a third negative
subunit located on the image side of the second positive subunit
with an air space; and
a third lens group of a positive refractive power, wherein at least
an air space between the first and second lens groups and an air
space between the second and third lens groups are changeable upon
zooming, wherein the lens system fulfills the following
condition:
wherein:
f.sub.II represents the focal length of the second lens group;
and
f.sub.II-2 represents the focal length of the second positive
subunit.
16. The invention of claim 15, wherein the condition for
.vertline.f.sub.II .vertline./f.sub.II-2 is as follows:
17. A zoom lens system of a relatively high zoom ratio ranging to
wide angle photography in which the shortest focal length is less
than the length of the diagonal line of the effective image plane,
comprising from the object to the image side:
a first lens group of a positive refractive power;
a second lens group of a negative refractive power consisting of a
first negative subunit including at least two separate negative
lenses, a second positive subunit located on the image side of the
first negative subunit with an unchangeable air space and a third
negative subunit located on the image side of the second positive
subunit with an unchangeable air space; and
a third lens group of a positive refractive power, wherein at least
an air space between the first and second lens groups and an air
space between the second and third lens groups are changeable upon
zooming, wherein the lens system fulfills the following
conditions:
wherein:
f.sub.w represents the shortest focal length of the whole lens
system; and
f.sub.I represents the focal length of the first lens group.
18. The invention of claim 17, wherein the whole first lens group
is movable for focusing with the other lens groups left
stationary.
19. A zoom lens system of a relatively high zoom ratio ranging to
wide angle photography in which the shortest focal length is less
than the length of the diagonal line of the effective image plane,
comprising from the object to the image side:
a first lens group of a positive refractive power;
a second lens group of a negative refractive power consisting of a
first negative subunit including at least two separate negative
lenses, a second positive subunit located on the image side of the
first negative subunit with an unchangeable air space and a third
negative subunit located on the image side of the second positive
subunit with an unchangeable air space; and
a third lens group of a positive refractive power, wherein at least
an air space between the first and second lens groups and an air
space between the second and third lens groups are changeable upon
zooming, wherein the lens system fulfills the following
condition:
wherein:
f.sub.I II represents the total focal length of the first and
second lens groups at the shortest focal length of the whole lens
system; and
f.sub.w represents the shortest focal length of the whole lens
system.
20. The invention of claim 19, wherein the lens system fulfills the
following conditions:
wherein:
f.sub.II represents the focal length of the second lens group;
and
f.sub.T represents the longest focal length of the whole lens
system.
21. The invention of claim 19, wherein the condition for
.vertline.f.sub.I II .vertline./f.sub.w is as follows:
22. The invention of claim 21, wherein the second lens group is
left stationary upon zooming.
23. A zoom lens system of a relatively high zoom ratio ranging to
wide angle photography in which the shortest focal length is less
than the length of the diagonal line of the effective image plane,
comprising from the object to the image side:
a first lens group of a positive refractive power;
a second lens group of a negative refractive power consisting of a
first negative subunit including at least two separate negative
lenses, a second positive subunit located on the image side of the
first negative subunit with an unchangeable air space and a third
negative subunit located on the image side of the second positive
subunit with an unchangeable air space; and
a third lens group of a positive refractive power, wherein at least
an air space between the first and second lens groups and an air
space between the second and third lens groups are changeable upon
zooming, wherein the lens system fulfills the following
condition:
wherein:
f.sub.II-1 represents the focal length of the first negative
subunit; and
f.sub.II represents the focal length of the second lens group.
24. The invention of claim 23, wherein the condition for f.sub.II-1
/f.sub.II is as follows:
25. The invention of claim 24, wherein the condition for f.sub.II-1
/f.sub.II is as follows:
26. The invention of claim 15, wherein the lens system further
fulfills the following condition:
wherein:
f.sub.w represents the shortest focal length of the whole lens
system; and
f.sub.I represents the focal length of the first lens group.
27. A zoom lens system of a relatively high zoom ratio ranging to
wide angle photography comprising the following design parameters:
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a zoom lens system of a high zoom
ratio greater than 2.3 ranging from a telephoto to wide field angle
for use in a still camera, such as 35 mm SLR cameras.
2. Description of the Prior Art
In this field of art, there has been various attempts to provide a
zoom lens system of a relatively high zoom ratio ranging to wide
field angle. Prior art zoom lens systems attempting to achieve
these results can be roughly classified into two types, the first
one having a negative front lens group, while the second one having
a positive front lens group.
The first type is in its nature favorable to the purpose of
providing the wide angle zoom lens system, while it is unfavorable
to the reducing the total length thereby providing a compactness to
the lens system. A most popular and simplified zoom lens system
that can be classified as a first type is a so-called two-group
zoom lens system consisting of a negative front lens group and a
positive rear lens group. Although such a two-group zoom lens
system is suitable for a limited zoom ratio, such as 2, it is
difficult to further increase the zoom ratio. In other words, if
the zoom ratio in the two-group zoom lens system is attempted to be
increased so as to range to a focal length greater than 85 mm in
terms of a 35 mm SLR camera, the manufacturing errors of air spaces
between the lens elements greatly influence the correction of
spherical aberration in the longer focal length range to thereby
fail in providing any practical and reliable product.
On the other hand, in the second type of zoom lens system with the
front positive lens group, if the zoom range is extended to reach a
focal length less than the length of a diagonal line of the
effective image plane, the focusing by means of moving the front
positive lens group is difficult or the diameter of the front
positive lens group is excessively increased. A typical example of
a zoom lens system classified into the second type is a so-called
four-group zoom lens system consisting of a front focusing lens
group, a variator lens group, a compensator lens group and a relay
lens group. In such a four-group zoom lens system, if the zoom
range is attempted to be extended to a focal length less than 40 mm
with the focusing capability by means of the front lens group and
the compactness of the whole lens system maintained, the focal
lengths of the front lens group and the variator lens group become
excessively short to cause various abberrations which are difficult
to be sufficiently corrected.
Examples of patented prior art literature can be found in U.S. Pat.
No. 4,256,381 and U.S. Pat. No. 4,299,454.
The prior art is still seeking to provide a relatively compact and
economical zoom lens system having a relatively wide range of
zooming into the wide angle range with adequate optical
correction.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a zoom lens system
with a relatively high zoom ratio ranging to a wide field angle
while maintaining a compact size.
Another object of the present invention is to provide a zoom lens
system with aberrations well corrected across the entire zoom
range.
Still another object of the present invention is to provide a zoom
lens system with an increased tolerance to any manufacturing
error.
A further object of the present invention is to provide a zoom lens
system with both an increased speed and increased zoom ratio.
A still further object of the present invention is to provide a
zoom lens system with a relatively high zoom ratio ranging to a
wide field angle capable of focusing by means of moving the front
lens group.
A still another further object of the present invention is to
provide a zoom lens system with a wide zoom range such as 35-80 mm,
35-100 mm, 35-105 mm, 35-135 mm, 35-150 mm and 35-200 mm with
respect to 35 mm SLR cameras.
According to the present invention, a zoom lens system is provided,
which comprises a first positive lens group, a second negative lens
group of a novel construcion which consists of a first negative
subgroup, a second positive subunit located on the image side of
the first negative subunit with an unchangeable air space and a
third negative subunit located on the image side of the second
positive subunit with an unchangeable air space, and a third
positive lens group, wherein at least the air space between the
first and second lens groups and the air space between the second
and third lens groups are changeable upon zooming. Further
according to another feature of the present invention, the focusing
is possible by means of moving the first lens group with the other
lens groups left stationary.
The features of the present invention which are believed to be
novel are set forth with particularity in the appended claims. The
present invention, both as to its organization and manner or
operation, together with further objects and advantages thereof,
may best be understood by reference to the following description,
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 represents a cross sectional view of a first embodiment of
the present invention;
FIG. 2 represents a cross sectional view of a second embodiment of
the present invention;
FIG. 3 represents a cross sectional view of a third embodiment of
the present invention;
FIG. 4 represents a cross sectional view of a fourth embodiment of
the present invention;
FIG. 5 represents a cross sectional view of a fifth embodiment of
the present invention;
FIG. 6 represents a cross sectional view of a sixth embodiment of
the present invention;
FIG. 7 represents a cross sectional view of a seventh embodiment of
the present invention;
FIG. 8 represents a cross sectional view of a eighth embodiment of
the present invention;
FIG. 9 represents a cross sectional view of a ninth embodiment of
the present invention;
FIG. 10 represents a cross sectional view of a tenth embodiment of
the present invention;
FIG. 11 represents a cross sectional view of a eleventh embodiment
of the present invention;
FIG. 12 represents a cross sectional view of a twelfth embodiment
of the present invention;
FIG. 13 represents a cross sectional view of a thirteenth
embodiment of the present invention;
FIG. 14 represents a cross sectional view of a fourteenth
embodiment of the present invention;
FIG. 15 represents a cross sectional view of a fifteenth embodiment
of the present invention;
FIG. 16 represents a cross sectional view of a sixteenth embodiment
of the present invention;
FIG. 17 represents a cross sectional view of a seventeenth
embodiment of the present invention;
FIGS. 18a, 18b and 18c represent aberration curves of the first
embodiment for the longest focal length;
FIGS. 19a, 19b and 19c represent aberration curves of the first
embodiment for the medium focal length;
FIGS. 20a, 20b and 20c represent aberration curves of the first
embodiment for the shortest focal length;
FIGS. 21a, 21b and 21c represent aberration curves of the second
embodiment for the longest focal length;
FIGS. 22a, 22b and 22c represent aberration curves of the second
embodiment for the medium focal length;
FIGS. 23a, 23b and 23c represent aberration curves of the second
embodiment for the shortest focal length;
FIGS. 24a, 24b and 24c represent aberration curves of the third
embodiment for the longest focal length;
FIGS. 25a, 25b and 25c represent aberration curves of the third
embodiment for the medium focal length;
FIGS. 26a, 26b and 26c represent aberration curves of the third
embodiment for the shortest focal length;
FIGS. 27a, 27b and 27c represent aberration curves of the fourth
embodiment for the longest focal length;
FIGS. 28a, 28b and 28c represent aberration curves of the fourth
embodiment for the medium focal length;
FIGS. 29a, 29b and 29c represent aberration curves of the fourth
embodiment for the shortest focal length;
FIGS. 30a, 30b and 30c represent aberration curves of the fifth
embodiment for the longest focal length;
FIGS. 31a, 31b and 31c represent aberration curves of the fifth
embodiment for the medium focal length;
FIGS. 32a, 32b and 32c represent aberration curves of the fifth
embodiment for the shortest focal length;
FIGS. 33a, 33b and 33c represent aberration curves of the sixth
embodiment for the longest focal length;
FIGS. 34a, 34b and 34c represent aberration curves of the sixth
embodiment for the medium focal length;
FIGS. 35a, 35b and 35c represent aberration curves of the sixth
embodiment for the shortest focal length;
FIGS. 36a, 36b and 36c represent aberration curves of the seventh
embodiment for the longest focal length;
FIGS. 37a, 37b and 37c represent aberration curves of the seventh
embodiment for the medium focal length;
FIGS. 38a, 38b and 38c represent aberration curves of the seventh
embodiment for the shortest focal length;
FIGS. 39a, 39b and 39c represent aberration curves of the eighth
embodiment for the longest focal length;
FIGS. 40a, 40b and 40c represent aberration curves of the eighth
embodiment for the medium focal length;
FIGS. 41a, 41b and 41c represent aberration curves of the eighth
embodiment for the shortest focal length;
FIGS. 42a, 42b and 42c represent aberration curves of the ninth
embodiment for the longest focal length;
FIGS. 43a, 43b and 43c represent aberration curves of the ninth
embodiment for the medium focal length;
FIGS. 44a, 44b and 44c represent aberration curves of the ninth
embodiment for the shortest focal length;
FIGS. 45a, 45b and 45c represent aberration curves of the tenth
embodiment for the longest focal length;
FIGS. 46a, 46b and 46c represent aberration curves of the tenth
embodiment for the medium focal length;
FIGS. 47a, 47b and 47c represent aberration curves of the tenth
embodiment for the shortest focal length;
FIGS. 48a, 48b and 48c represent aberration curves of the eleventh
embodiment for the longest focal length;
FIGS. 49a, 49b and 49c represent aberration curves of the eleventh
embodiment for the medium focal length;
FIGS. 50a, 50b and 50c represent aberration curves of the eleventh
embodiment for the shortest focal length;
FIGS. 51a, 51b and 51c represent aberration curves of the twelfth
embodiment for the longest focal length;
FIGS. 52a, 52b and 52c represent aberration curves of the twelfth
embodiment for the medium focal length;
FIGS. 53a, 53b and 53c represent aberration curves of the twelfth
embodiment for the shortest focal length;
FIGS. 54a, 54b and 54c represent aberration curves of the
thirteenth embodiment for the longest focal length;
FIGS. 55a, 55b and 55c represent aberration curves of the
thirteenth embodiment for the medium focal length;
FIGS. 56a, 56b and 56c represent aberration curves of the
thirteenth embodiment for the shortest focal length;
FIGS. 57a, 57b and 57c represent aberration curves of the
fourteenth embodiment for the longest focal length;
FIGS. 58a, 58b and 58c represent aberration curves of the
fourteenth embodiment for the medium focal length;
FIGS. 59a, 59b and 59c represent aberration curves of the
fourteenth embodiment for the shortest focal length;
FIGS. 60a, 60b and 60c represent aberration curves of the fifteenth
embodiment for the longest focal length;
FIGS. 61a, 61b and 61c represent aberration curves of the fifteenth
embodiment for the medium focal length;
FIGS. 62a, 62b and 62c represent aberration curves of the fifteenth
embodiment for the shortest focal length;
FIGS. 63a, 63b and 63c represent aberration curves of the sixteenth
embodiment for the longest focal length;
FIGS. 64a, 64b and 64c represent aberration curves of the sixteenth
embodiment for the medium focal length;
FIGS. 65a, 65b and 65c represent aberration curves of the sixteenth
embodiment for the shortest focal length;
FIGS. 66a, 66b and 66c represent aberration curves of the
seventeenth embodiment for the longest focal length;
FIGS. 67a, 67b and 67c represent aberration curves of the
seventeenth embodiment for the medium focal length; and
FIGS. 68a, 68b and 68c represent aberration curves of the
seventeenth embodiment for the shortest focal length.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description is provided to enable any person skilled
in the optical and camera field to make and use the invention and
sets forth the best modes contemplated by the inventors for
carrying out their invention. Various modifications, however, will
remain readily apparent to those skilled in the art, since the
generic principles of the present invention have been defined
herein specifically to provide an improved compact zoom lens system
with an increased zoom ratio ranging to a wide field angle. The
derivation of the formulas and the relation of the powers set forth
herein can be accomplished with the assistance of a computer. The
present invention represents the parameters of a compromise balance
of acceptable aberrations which can be relatively easily
manufactured to provide a low cost lens system for utilization with
a 35 mm SLR camera.
In the drawings, schematic cross sectional views disclose the
position of the lens group and lens elements for the respective
shortest focal length (S). Due to the number of lens elements
involved, it was not deemed appropriate to include individual
designation of the radius of curvature and axial distances for each
lens element and air space. These values, however, are provided in
the accompanying Tables set forth herein, and the schematic cross
sectional views of the respective embodiments follow the normal
conventions of an object at the left-hand side of the drawing and
the image plane at the right-hand side.
As disclosed in FIGS. 1 to 17, the present invention provides a
zoom lens system of a relatively high zoom ratio ranging to wide
angle photography in which the shortest focal length is less than
the length of diagonal line of the effective image plane comprising
from the object to the image side: a first lens group (I) of a
positive refractive power; a second lens group (II) of a negative
refractive power consisting of a first negative or subunit (II-1),
a second positive subunit (II-2) located on the image side of the
first negative subgroup (II-1) with an unchangeable air space and a
third negative subunit (II-3) located on the image side of the
second positive subgroup (II-2) with an unchangeable air space; and
a third lens group (III) of a positive refractive power, wherein at
least the air space between the first and second lens groups and
the air space between the second and third lens groups are
changeable upon zooming. The term "subunit" refers to one or more
lens elements while the term "group" refers to a plurality of lens
elements. As is apparent from the embodiments, the first negative
subunit (II-1) includes at least two separate negative lenses, the
absolute value of the radius of curvature being less on the image
side surface than on the object side surface with respect to the
object side one of the two separate negative lenses in the first
negative subunit (II-1). The second positive subunit (II-2)
includes at least one positive lens with an object side surface of
a lesser absolute value of radius of curvature and an image side
surface of a greater absolute value of radius of curvature. And,
the third negative subunit (II-3) includes at least one negative
lens with an object side surface of a lesser absolute value of
radius of curvature and an image side surface of a greater absolute
value of radius of curvature. Further, the first lens group (I) can
be moved for focusing with the other lens groups left
stationary.
According to another feature of the present invention the lens
system fulfills the following condition:
wherein:
R.sub.a represents the radius of curvature of the most image side
surface of the first negative subunit (II-1); and
R.sub.b represents the radius of curvature of the most object side
surface of the second positive subunit (II-2).
One of the most important features of the present invention resides
in the novel shape of the second negative lens group (II). The
first point of the novel shape of the second negative lens group
(II) is the use of the third negative subunit (II-3) located at the
image side end of the second lens group (II). In the prior art
classified into the type with a positive front lens group, a
typical shape of the conventional second negative lens group
consists of a first negative subunit and a second negative subunit,
at least one of which may be a doublet for the purpose of
correcting the chromatic aberration if necessary. Another
conventional second negative lens group consists of a first
negative subunit, a second negative subunit and a third positive
subunit for the purpose of balancing the spherical aberration by
means of the combination of the second and third subunits if an
intolerable variation in the spherical aberration will be caused by
zooming. These conventional shapes are, however, only practical in
the case of a relatively weak refractive power of the second
negative lens group which is suitable for a telephoto zoom lens
system. On the other hand, according to the present invention, the
third negative subunit (II-3) is used in combination with the first
negative subunits (II-1) and the second positive subunits (II-2) to
strengthen the negative refractive power of the second negative
lens group (II) and to shorten the image side focal length of the
second negative lens group (II), which is effective for reducing
the thin lens air space between the second and third lens groups to
achieve a compact size for the whole lens system.
The second point of the feature relating to the shape of the second
negative lens group (II) is the shapes of the most image side
surface (R.sub.a) of the first negative subunit (II-1) and the most
object side surface (R.sub.b) of the second positive subunit
(II-2). In order words, the above condition (1) defines the shape
of these surfaces for reducing the variation in spherical
aberration upon zooming although the second negative lens group
(II) of the present invention has a greater negative refractive
power than the conventional one. The most object side surface
(R.sub.b) of the second positive subunit (II-2) fulfilling
condition (1) is effective to cause a negative deviation of the
spherical aberration to moderate the positive deviation of the
spherical aberration inherent to the whole second negative lens
group (II), which reduces the variation in spherical
aberration.
With respect to the shape of the second negative lens group (II),
the present invention further provides the following
conditions:
wherein:
.PHI. represents the refractive power of the air lens formed
between the second positive subunit (II-2) and the third negative
subunit (II-3);
f.sub.II represents the focal length of the second lens group
(II);
f.sub.II-1 represents the focal length of the first negative
subunit (II-1); and
f.sub.II-2 represents the focal length of the second positive
subunit (II-2).
Condition (2) relates to condition (1) and the correction of the
spherical aberration. As has been stated, the shapes of the pair of
surfaces forming the unchangeable air lens between the first and
second subunits defined by condition (1) causes the negative
diviation of the spherical aberration. However, if the negative
deviation of the spherical aberration is sufficiently caused to
correct the lower degree of spherical aberration, the higher degree
of spherical aberration will be rather excessively corrected. The
air unchangeable lens between the second and third subunits
fulfilling condition (2) is effective to cancel such an excessive
correction of the higher degree of spherical aberration.
Condition (3) relatively defines the refractive power of the second
positive subunit (II-2) for correcting the spherical aberration of
the second lens group (II) having a greater negative refractive
power than in the conventionalone. If the lower limit is violated,
an excessive negative deviation of spherical aberration would be
caused in the whole second negative lens group (II). On the other
hand, if the upper limit is violated, the negative refractive
powers of the first subunit (II-1) and the third subunit (II-3)
would have to be excessively strong to fail in correcting coma,
especially at the balance between the shortest and medium focal
lengths of the whole lens system.
Condition (4) is more preferably as follows:
and defines the refractive power of the first negative subunit
(II-1). Any violation of the lower limit would cause an excessive
negative refractive power of the first subunit (II-1), which should
be cancelled by an excessive positive refractive power of the
second positive subunit (II-2). Such excessive refractive powers
would fail in achieving any practical speed of the lens system and
make the adoption of the third negative subunit (II-3) meaningless.
On the other hand, if the upper limit is violated, the third
negative subunit (II-3) would have to be burdened with an excessive
negative refractive power to fail in sufficiently correcting the
distortion at the shortest focal length, and the above mentioned
second point of the feature of the second lens group (II) relating
to condition (1) would no longer be effective.
With respect to the feature of the focusing by means of moving the
first lens group (I), the present invention provides the following
condition:
wherein:
f.sub.w represents the shortest focal length of the whole lens
system; and
f.sub.I represents the focal length of the first lens group.
Condition (5) defines the refractive power of the first lens group
(I). If the upper limit is violated, the distortion would be
increased especially at the longest focal length of the whole lens
system. On the other hand, if the lower limit is violated, the
closest object distance practically attained by means of moving the
first lens group (I) with the other lens groups left stationary
would be unsatisfactory.
Further, according to the present invention, the following
conditions are provided:
wherein:
f.sub.I II represents the total focal length of the first and
second lens groups at the shortest focal length; and
f.sub.III represents the focal length of the third lens group
(III).
Condition (6) is for extending the shortest focal length into the
wide field angle range and for realizing a necessary change in the
air space between the first and second lens groups. If the lower
limit is violated, the movement of the first lens group (I) is
impractically increased if it is moved upon zooming. On the other
hand, the violation of the upper limit is unfavorable to a zoom
lens system including a wide field angle range. In the case of a
telephoto zoom lens system, the value for .vertline.f.sub.I II
.vertline./f.sub.w is over the upper limit, and it is difficult to
extend the zoom range into the wide field angle since the diameter
of the lens group would be extremely increased or the illumination
at the marginal area would become insufficient.
Condition (7) defines a practical range for the refractive power of
the third lens group (III). If the lower limit is violated, the
refractive powers of the second and third lens groups are both
excessive as long as condition (5) is fulfilled, which results in a
difficulty of correcting aberrations. While, the desired
compactness would be no more attained if the upper limit is
violated.
Condition (8) further defines a practical refractive power of the
third lens group (III). If the lower limit is violated, the desired
zoom type of the present invention would be impossible. And, the
violation of the upper limit means a case of an insufficiency of
the shortest focal length of the whole lens system deviating from
the object of the present invention or a case of an extremely short
focal length of the first lens group (I) resulting in a difficulty
of any practical aberration correction.
In the above conditions, condition (6) can be reduced as follows if
some specific demands exist:
In the reduced range of condition (6)', the second lens group can
be left stationary upon zooming to simplify the control of the lens
group movement. Further, in the reduced range of condition (6)', a
focusing by means of moving the second lens group (II) toward the
object side within the whole zoom range is possible. In this case
of focusing by means of the second lens group, an air space should
be secured between the first and second lens groups at the shortest
focal length of the whole lens system for allowing the movement of
the second lens group toward the object side upon focusing.
Although, such a focusing by means of moving a lens group other
than the first lens group shows a difference in the movement for
focusing a same object distance depending upon the focal length of
the whole lens system, there will be no problem if the lens
movement is to be controlled by an electric means such as in an
automatic focus control camera.
In a practical design of a zoom lens system according to the
present invention, the third lens group (III) is further divided
into a first subunit (III-1) and a second subunit (III-2), the air
space between the first and second subunits in the third lens group
(III) being further changeable upon zooming. Such a division should
be made so that the rays in the paraxial light pencil transmitted
between the first subunit (III-1) and the second subunit (III-2)
are substantially paralel with the optical axis. The change in such
an air space in the third lens group (III) upon zooming is
effective to correct the variation in astigmatism during
zooming.
Further, in a practical design, it is recommended to adopt at least
one doublet as a lens in the second lens group (II) for correcting
the variation in chromatic aberration, especially the lateral
chromatic aberration which would be caused by the relatively great
refractive power of the second lens group (II).
The following Tables 1 to 17 disclose, respectively, the first
through seventeenth embodiments of the present invention. In the
Tables, f equals the focal length, r is the radius of curvature
with respective sub numbers indicating the surfaces from the object
to image side along the optical axis, d represents the axial
distance and includes both the air spaces and the actual thickness
of the lens components along the optical axis, N equals the
refractive index and again, the sub numbers refer to the particular
optical element from the object to image side, and finally, .nu.
equals the Abbe number and the sub numbers refer to the specific
lens elements from the object to image side. The variable air space
distances, in the Tables are provided with three separate values
that disclose the relative displacement between each of the
respective focal lengths.
TABLE 1 ______________________________________ [Embodiment 1] f =
36.0.about.60.0.about.97.0 F.sub.No. = 3.6.about.4.6 Radius of
Axial Refractive Abbe Curvature Distance Index Number
______________________________________ ##STR1##
r.sub.1r.sub.2r.sub.3 73.361126.72743.958 d.sub.1d.sub.2 3.5000.100
N.sub.1 1.69680 .nu..sub.1 55.5 ##STR2## r.sub.4r.sub.5
28.169182.209 d.sub.3d.sub.4 1.2008.500 N.sub.2N.sub.3
1.846661.69680 .nu..sub.2.nu..sub.3 23.955.5 d.sub.5
0.600.about.7.989.about.15.809 ##STR3## r.sub.
6r.sub.7r.sub.8r.sub.9 81.16314.454-140.01929.775
d.sub.6d.sub.7d.sub.8d.sub.9 1.3005.5001.0000.100 N.sub.4N.sub.5
1.670001.67000 .nu..sub.4.nu..sub.5 57.157.1 ##STR4##
r.sub.10r.sub.11r.sub.12r.sub.13 21.595154.105-33.009-186.185
d.sub.10d.sub.11d.sub.12 3.1501.8001.000 N.sub.6N.sub.7
1.805181.67000 .nu..sub.6.nu..sub.7 25.457.1 d.sub.13
18.500.about.9.152.about.1.861 ##STR5##
r.sub.14r.sub.15r.sub.16r.sub.17r.sub.18 -507.640-34.024
17.485-23.10557.327 d.sub.14d.sub.15d.sub.16d.sub.17d.sub.18
2.500N.sub.81.62135.nu..sub.861.30.1506.000N.s
ub.91.51454.nu..sub.1054.74.000N.sub.101.80741.
nu..sub.1031.610.000.about.8.300.about.7.100 ##STR6##
r.sub.19r.sub.20r.sub.21r.sub.22 364.870-20.606-14.158-23.398
d.sub.19d.sub.20d.sub.21 4.0004.0001.500 N.sub.11N.sub.12
1.666081.80750 .nu..sub.11.nu..sub.12 47.935.5
______________________________________
TABLE 2 ______________________________________ [Embodiment 2] f =
36.0.about.60.0.about.97.0 F.sub.No. = 3.6.about.4.6 Radius of
Axial Refractive Abbe Curvature Distance Index Number
______________________________________ ##STR7##
r.sub.1r.sub.2r.sub.3 100.00041.322250.300 d.sub.1d.sub.2
1.7007.500 N.sub.1N.sub.2 1.805181.69680 .nu..sub.1.nu..sub.2
25.455.5 ##STR8## r.sub.4r.sub.5 43.852176.326 d.sub.3d.sub.4
0.1004.500 N.sub.3 1.69680 .nu..sub.3 55.5 d.sub.5
0.600.about.9.261.about.17.393 ##STR9## r.sub.6
r.sub.7r.sub.8r.sub.9 67.41214.963-231.85731.696
d.sub.6d.sub.7d.sub.8 1.3005.9001.000 N.sub.4N.sub.5 1.670001.67000
.nu..sub.4.nu..sub.5 57.157.1 ##STR10## r.sub.10r.sub.11
21.783214.482 d.sub.9d.sub.10d.sub.11 0.1003.3001.923 N.sub.6
1.80518 .nu..sub.6 25.4 ##STR11## r.sub.12r.sub.13r.sub.14r.sub.15
-34.06683.10560.00293.246 d.sub.12d.sub.13d.sub.14 1.0000.1002.000
N.sub.7N.sub.8 1.670001.74400 .nu..sub.7.nu..sub.7 57.144.9
d.sub.15 18.000.about. 9.479.about.2.401 ##STR12##
r.sub.16r.sub.17r.sub.18 -812.018-32.61417.818 d.sub.16d.sub.17
2.5000.150 N.sub.9 1.62135 .nu..sub.9 61.3 ##STR13##
r.sub.19r.sub.20 -23.32663.062 d.sub.18d.sub.19 6.0004.000
N.sub.10N.sub.11 1.501371.80741 .nu..sub.10.nu..sub.11 56.431.6
##STR14## r.sub.21r.sub.22 356.557-23.366 d.sub.20d.sub.21d.sub.22
10.000.about.8.300.about.7.1004.000N.sub.121.6
7830.nu..sub.1249.05.800 ##STR15## r.sub.23r.sub.24 -14.626-23.999
d.sub.23 1.500 N.sub.13 1.80750 .nu..sub.13 35.5
______________________________________
TABLE 3 ______________________________________ [Embodiment 3] f =
36.0.about.60.0.about.97.0 F.sub.No. = 3.6.about.4.6 Radius of
Axial Refractive Abbe Curvature Distance Index Number
______________________________________ ##STR16##
r.sub.1r.sub.2r.sub.3 100.0041.322222.539 d.sub.1d.sub.2 1.7007.500
N.sub.1N.sub.2 1.805181.69680 .nu..sub.1.nu..sub.2 25.455.5
##STR17## r.sub.4r.sub.5 41.621154.849 d.sub.3d.sub.4 0.1004.700
N.sub.3 1.69680 .nu..sub.3 55.5 d.sub.5
0.600.about.8.800.about.16.809 ##STR18## r.sub.6r.sub. 7r.sub.8
72.74315.934-171.978 d.sub.6d.sub.7d.sub.8 1.3006.0002.000 N.sub.4
N.sub.5 1.67000 1.74400 .nu..sub.4 .nu..sub.5 57.1 44.9 ##STR19##
r.sub.9r.sub.10r.sub.11 -65.535-74.14729.596
d.sub.9d.sub.10d.sub.11 0.5001.0000.100 N.sub.6 1.67000 .nu..sub.6
57.1 ##STR20## r.sub.12r.sub.13 22.219202.910 d.sub.12d.sub.13
3.3001.742 N.sub.7 1.80518 .nu..sub.7 25.4 ##STR21##
r.sub.14r.sub.15 -34.299179.762 d.sub.14 1.000 N.sub.8 1.67000
.nu..sub.8 57.1 d.sub.15 17.500.about.8.869.about.1.804 ##STR22##
r.sub.16r.sub.17r.sub.18 -812.018-31.14317.895 d.sub.16d.sub.17
2.5000.150 N.sub.9 1.62135 .nu..sub.9 61.3 ##STR23##
r.sub.19r.sub.20 -23.48663.062 d.sub.18d.sub.19d.sub.20
6.000N.sub.101.50137.nu..sub.1056.44.000N.sub.
111.80741.nu..sub.1131.610.00.about.8.300.about .7.100 ##STR24##
r.sub.21r.sub.22 334.840-23.429 d.sub.21 4.000 N.sub.12 1.67100
.nu..sub.12 51.8 ##STR25## r.sub.23r.sub.24 -14.642-23.898
d.sub.22d.sub.23 5.8001.500 N.sub.13 1.80750 .nu..sub.13 35.5
______________________________________
TABLE 4 ______________________________________ [Embodiment 4] f =
36.0 .about.60.0.about.97.0 F.sub.No. = 3.6.about.4.6 Radius of
Axial Refractive Abbe Curvature Distance Index Number
______________________________________ ##STR26##
r.sub.1r.sub.2r.sub.3 100.00041.667161.207 d.sub.1d.sub.2
1.7006.000 N.sub.1N.sub.2 1.805181.69680 .nu..sub.1.nu..sub.2
25.455.5 ##STR27## r.sub.4r.sub.5 46.432472.657 d.sub.3d.sub.4
0.1005.000 N.sub.3 1.69680 .nu..sub.3 55.5 d.sub.5
0.600.about.9.232.about.17.282 ##STR28## r.sub.
6r.sub.7r.sub.8r.sub.9 76.49414.824-288.55930.217
d.sub.6d.sub.7d.sub.8 1.3005.0001.000 N.sub.4N.sub.5 1.677901.67000
.nu..sub.4.nu..sub.5 55.457.1 ##STR29##
r.sub.10r.sub.11r.sub.12r.sub.13 21.171581.057-27.987-315.766
d.sub.9d.sub.10d.sub.11d.sub.12 0.1003.3001.8501.000 N.sub.6N.sub.7
1.805181.67830 .nu..sub.6.nu..sub.7 25.449.0 d.sub.13
19.500.about.9.841.about.1.627 ##STR30## r.sub.14r.sub.15r.sub.16
306.401-31.01731.608 d.sub.14 d.sub.15d.sub.16 3.0000.1503.000
N.sub.8N.sub.9 1.516801.51728 .nu..sub.8.nu..sub.9 64.169.4
##STR31## r.sub.17r.sub.18r.sub.19r.sub.20
155.96516.93741.363-90.315 d.sub.17d.sub.18d.sub.19 0.1003.0003.100
N.sub.10 1.51728 .nu..sub.10 69.4 ##STR32## r.sub.21.sub.22r.sub.23
19.765149.356-25.469 d.sub.20d.sub.21d.sub.22 3.0004.0004.000
N.sub.11N.sub.12 1.805181.60565 .nu..sub.11.nu..sub.12 25.437.8
______________________________________
TABLE 5 ______________________________________ [ Embodiment 5] f =
36.0.about.60.0.about.97.0 F.sub.No. = 3.6.about.4.6 Radius of
Axial Refractive Abbe Curvature Distance Index Number
______________________________________ ##STR33##
r.sub.1r.sub.2r.sub.3 111.11143.478295.194 d.sub.1d.sub.2
1.7007.500 N.sub.1N.sub.2 1.805181.69680 .nu..sub.1.nu..sub.2
25.455.5 ##STR34## r.sub.4r.sub.5 43.521182.083 d.sub.3d.sub.4
0.1004.500 N.sub.3 1.69680 .nu..sub.3 55.5 d.sub.5
0.800.about.7.086.about.15.253 ##STR35## r.sub.6r.sub. 7r.sub.8
92.92416.759-192.374 d.sub.6d.sub.7 1.3006.000 N.sub.4 1.74400
.nu..sub.4 44.9 ##STR36## r.sub.9r.sub.10r.sub.11
37.02424.946-100.000 d.sub.8d.sub.9d.sub.10 1.0000.1003.800
N.sub.5N.sub.6 1.696801.80518 .nu..sub.5.nu..sub.6 55.525.4
##STR37## r.sub.12r.sub.13r.sub.14 154.409-34.832-173.810
d.sub.11d.sub.12d.sub.13 1.0002.0001.000 N.sub.7N.sub.8
1.667551.69680 .nu..sub.7.nu..sub.8 42.055.5 d.sub.14
20.876.about.10.027.about.2.000 ##STR38## r.sub.15r.sub.16r.sub.17
28818.416-36.75517.914 d.sub.15d.sub.16 2.5000.100 N.sub.9 1.62135
.nu..sub.9 61.3 ##STR39## r.sub.18r.sub.19 -23.48357.020
d.sub.17d.sub.18d.sub.19
6.500N.sub.101.52133.nu..sub.1051.12.000N.sub.
111.80741.nu..sub.1131.611.00.about.9.300.about .8.200 ##STR40##
r.sub.20r.sub.21 906.535-23.143 d.sub.20d.sub.21 4.0005.800
N.sub.12 1.67790 .nu..sub.12 55.4 ##STR41## r.sub.22r.sub.23
-14.444-24.692 d.sub.22 1.500 N.sub.13 1.80750 .nu..sub.13 35.5
______________________________________
TABLE 6 ______________________________________ [Embodiment 6] f =
36.0.about.60.0.about.97.0 F.sub.No. = 3.6.about.4.6 Radius of
Axial Refractive Abbe Curvature Distance Index Number
______________________________________ ##STR42##
r.sub.1r.sub.2r.sub.3 111.11144.444302.938 d.sub.1d.sub.2
1.7007.500 N.sub.1N.sub.2 1.805181.69680 .nu..sub.1.nu..sub.2
25.455.5 ##STR43## r.sub.4r.sub.5 43.716179.572 d.sub.3d.sub.4
0.1004.700 N.sub.3 1.69680 .nu..sub.3 55.5 d.sub.5
0.800.about.6.880.about.14.837 ##STR44## r.sub.6r.sub. 7r.sub.8
116.172-181.81816.378 d.sub.6d.sub.7 2.5001.300 N.sub.4N.sub.5
1.805181.74400 .nu..sub.4.nu..sub.5 25.444.9 ##STR45##
r.sub.9r.sub.10 -210.93938.270 d.sub.8d.sub.9d.sub.10
6.0001.0000.100 N.sub.6 1.69680 .nu..sub.6 55.5 ##STR46##
r.sub.11r.sub.12 24.705168.276 d.sub.11d.sub.12 3.8002.000 N.sub.7
1.80518 .nu..sub.7 25.4 ##STR47## r.sub.13r.sub.14 -34.000-140.060
d.sub.13 1.000 N.sub.8 1.69680 .nu..sub.8 55.5 d.sub.14
20.350.about.9.796.about.2.000 ##STR48## r.sub.15r.sub.16r.sub.17
1453.910-35.43817.778 d.sub.15d.sub.16 2.5000.100 N.sub.9 1.62135
.nu..sub.9 61.3 ##STR49## r.sub.18r.sub.19 -23.16857.326
d.sub.17d.sub.18d.sub.19
6.500N.sub.101.51602.nu..sub.1056.82.000N.sub.
111.80741.nu..sub.1131.610.761.about.9.061.abou t.7.961 ##STR50##
r.sub.20r.sub.21 2753.303-23.278 d.sub.20d.sub.21 4.0005.800
N.sub.12 1.71060 .nu..sub.12 43.3 ##STR51## r.sub.22r.sub.23
-14.394-25.060 d.sub.22 1.500 N.sub.13 1.80750 .nu..sub.13 35.5
______________________________________
TABLE 7 ______________________________________ [Embodiment 7] f =
26.0.about.50.0.about.82.5 F.sub.No. = 3.6 Radius of Axial
Refractive Abbe Curvature Distance Index Number
______________________________________ ##STR52## r.sub.1 r.sub.2
r.sub.3 100.000 41.667 342.079 d.sub.1 d.sub.2 1.700 11.000 N.sub.1
N.sub.2 1.80518 1.69680 .nu..sub.1 .nu..sub.2 25.4 55.5 ##STR53##
r.sub.4 r.sub.5 39.404 154.373 d.sub.3 d.sub.4 0.100 7.000 N.sub.3
1.69680 .nu..sub.3 55.5 d.sub.5 0.700 8.145 17.142 ##STR54##
r.sub.6 r.sub.7 r.sub.8 74.521 14.139 -165.046 d.sub.6 d.sub.7
1.300 6.444 N.sub.4 1.65830 .nu..sub.4 58.4 ##STR55## r.sub.9
r.sub.10 32.188 21.488 d.sub.8 d.sub.9 d.sub.10 1.200 0.100 3.500
N.sub.5N.sub.6 1.666081.80518 .nu..sub.5.nu..sub.6 47.925.4
##STR56## r.sub.11 r.sub.12 r.sub.13 238.282 -33.430 2734.481
d.sub.11 d.sub.12 2.000 1.200 N.sub.7 1.65830 .nu..sub.7 58.5
d.sub.13 18.000.about.7.752.about.1.000 ##STR57## r.sub.14 r.sub.15
r.sub.16 -69.231 -618.085 246.731 d.sub.14 d.sub.15 1.200N.sub.
81.67830.nu..sub.849.02.000.about. 4.803.about.2.557 ##STR58##
r.sub.17 r.sub.18 -30.782 17.982 d.sub.16 d.sub.17 d.sub.18 2.500
0.100 6.000 N.sub.9N.sub.10 1.617201.51602 .nu..sub.9.nu..sub.10
54.056.8 ##STR59## r.sub.19 r.sub.20 r.sub.21 -21.252 65.361
220.819 d.sub.19 d.sub.20 d.sub.21 2.000 8.500 4.000
N.sub.11N.sub.12 1.807501.67830 .nu..sub.11.nu..sub.12 35.549.0
##STR60## r.sub.22 r.sub.23 r.sub.24 -22.561 -14.300 -23.891
d.sub.22 d.sub.23 5.500 2.000 N.sub.13 1.80518 .nu..sub.13 25.4
______________________________________
TABLE 8 ______________________________________ [Embodiment 8] f =
35.9.about.60.0.about.102.7 F.sub.No. = 3.6 Radius of Axial
Refractive Abbe Curvature Distance Index Number
______________________________________ ##STR61## r.sub.1 r.sub.1
r.sub.3 60.995 36.364 127.846 d.sub.1 d.sub.2 2.000 9.885 N.sub.1
N.sub.2 1.80518 1.69100 .nu..sub.1 .nu..sub.2 25.46 54.75 ##STR62##
r.sub.4 r.sub.5 51.451 186.334 d.sub.3 d.sub.4 0.186 5.300 N.sub.3
1.69100 .nu..sub.3 54.75 d.sub.5 1.000.about.13.240.about.23.074
##STR63## r.sub.6 r.sub.7 r.sub.8 92.332 15.042 -109.196 d.sub.6
d.sub.7 1.500 5.000 N.sub.4 1.75450 .nu..sub.4 51.57 ##STR64##
r.sub.9 r.sub.10 37.375 24.134 d.sub.18 d.sub.9 d.sub.10 1.500
0.500 3.500 N.sub.5N.sub.6 1.696801.80518 .nu..sub.5.nu..sub.6
55.5225.43 ##STR65## r.sub.11 r.sub.12 r.sub.13 516.916 -35.786
875.158 d.sub.11 d.sub.12 1.500 1.500 N.sub.7 1.69680 .nu..sub.7
55.52 d.sub.13 15.783.about.8.662.about.1.000 ##STR66## r.sub.14
r.sub.15 r.sub.16 105.116 -62.507 38.142 d.sub.14 d.sub.15 3.500
0.150 N.sub.8 1.58913 .nu..sub.8 61.11 ##STR67## r.sub.17 r.sub.18
-100.000 269.158 d.sub.16 d.sub.17 d.sub.18
3.000N.sub.91.53241.nu..sub.951.541.500N.sub.1
01.80518.nu..sub.1025.4310.150.about.4.950.abou t.2.650 ##STR68##
r.sub.19 r.sub.20 r.sub.21 24.446 104.300 -61.484 d.sub.19 d.sub.20
2.923 3.697 N.sub.11 1.60565 .nu..sub.11 37.81 ##STR69## r.sub.22
r.sub.23 29.010 -447.079 d.sub.21 d.sub.22 d.sub.23 2.471 4.068
3.431 N.sub.12N.sub.13 1.805181.56883 .nu..sub.12.nu..sub.13
25.4356.04 ##STR70## r.sub.24 r.sub.25 r.sub.26 -28.052 49.214
-216.413 d.sub.24 d.sub.25 0.200 4.558 N.sub.14 1.57616 .nu..sub.14
41.42 ______________________________________
TABLE 9 ______________________________________ [ Embodiment 9] f =
35.9.about.60.0.about.102.7 F.sub.No. = 3.6 Radius of Axial
Refractive Abbe Curvature Distance Index Number
______________________________________ ##STR71## r.sub.1 r.sub.2
r.sub.3 166.667 54.054 -4219.406 d.sub.1 d.sub.2 2.000 6.200
N.sub.1 N.sub.2 1.80518 1.69100 .nu..sub.1 .nu..sub.2 25.46 54.75
##STR72## r.sub.4 r.sub.5 45.669 185.307 d.sub.3 d.sub.4 0.186
4.800 N.sub.3 1.69100 .nu..sub.3 54.75 d.sub.5
1.00.about.12.505.about.24.288 ##STR73## r.sub.6 r.sub.7 r.sub.8
r.sub.9 87.438 15.312 -475.561 36.452 d.sub.6 d.sub.7 d.sub.8 1.500
3.600 1.500 N.sub.4N.sub.5 1.754501.69680 .nu..sub.4.nu..sub.5
51.5755.52 ##STR74## r.sub.10 r.sub.11 22.902 311.710 d.sub.9
d.sub.10 d.sub.11 0.500 3.500 1.300 N.sub.6 1.80518 .nu..sub.6
25.43 ##STR75## r.sub.12 r.sub.13 r.sub.14 -34.414 20.000 88.423
d.sub.12 d.sub.13 1.000 3.000 N.sub.7 N.sub.8 1.72000 1.80700
.nu..sub.7 .nu..sub.8 50.31 39.75 d.sub.14
15.067.about.8.064.about.1.501 ##STR76## r.sub.15 r.sub.16 r.sub.17
94.309 -70.626 34.234 d.sub.15 d.sub.16 3.500 0.150 N.sub.9 1.58913
.nu..sub.9 61.11 ##STR77## r.sub.18 r.sub.19 -100.000 143.605
d.sub.17 d.sub.18 3.000 1.500 N.sub.10 N.sub.11 1.53241 1.80518
.nu..sub.10 .nu..sub.11 51.54 25.43 ##STR78## r.sub.20 r.sub.21
26.274 113.387 d.sub.19 d.sub.20 d.sub.21
8.155.about.4.155.about.1.6553.484N.sub.121.60
565.nu..sub.1237.814.239 ##STR79## r.sub.22 r.sub.23 r.sub.24
-56.891 30.792 -194.584 d.sub.22 d.sub.23 d.sub.24 4.521 1.822
3.431 N.sub.13N.sub.14 1.805181.56994 .nu..sub.13.nu..sub.14
25.4348.06 ##STR80## r.sub.25 r.sub.26 r.sub.27 -28.877 41.681
-117.383 d.sub.25 d.sub.26 0.200 4.670 N.sub.15 1.57616 .nu..sub.15
41.42 ______________________________________
TABLE 10 ______________________________________ [ Embodiment 10] f
= 35.9.about.60.0.about.102.7 F.sub.No. = 3.6 Radius of Axial
Refractive Abbe Curvature Distance Index Number
______________________________________ ##STR81## r.sub.1 r.sub.2
r.sub.3 166.667 53.476 -876.846 d.sub.1 d.sub.2 2.000 6.200 N.sub.1
N.sub.2 1.80518 1.69100 .nu..sub.1 .nu..sub.2 25.46 54.75 ##STR82##
r.sub.4 r.sub.5 44.857 192.500 d.sub.3 d.sub.4 0.186 4.800 N.sub.3
1.69100 .nu..sub.3 54.75 d.sub.5 1.000.about.11.375.about.20.716
##STR83## r.sub.6 r.sub.7 r.sub.8 r.sub.9 94.404 15.312 -403.302
37.341 d.sub.6 d.sub.7 d.sub.8 1.500 3.600 1.500 N.sub.4N.sub.5
1.754501.69680 .nu..sub.4.nu..sub.5 51.5755.52 ##STR84## r.sub.10
r.sub.11 22.520 245.926 d.sub.9 d.sub.10 d.sub.11 0.500 3.500 1.600
N.sub.6 1.80518 .nu..sub.6 25.43 ##STR85## r.sub.12 r.sub.13
r.sub.14 -33.498 20.000 74.385 d.sub.12 d.sub.13 1.000 3.000
N.sub.7 N.sub.8 1.72000 1.80700 .nu..sub.7 .nu..sub.8 50.31 39.75
d.sub.14 14.717.about.7.985.about.1.500 ##STR86## r.sub.15 r.sub.16
r.sub.17 92.618 -69.103 33.553 d.sub.15 d.sub.16 3.500 0.150
N.sub.9 1.58913 .nu..sub.9 61.11 ##STR87## r.sub.18 r.sub.19
-100.000 148.223 d.sub.17 d.sub.18 3.000 1.500 N.sub.10 N.sub.11
1.53241 1.80518 .nu..sub.10 .nu..sub.11 51.54 25.43 ##STR88##
r.sub.20 r.sub.21 25.877 122.950 d.sub.19 d.sub.20 d.sub.21
8.181.about.4.181.about.1.6813.556N.sub.121.60
565.nu..sub.1237.814.344 ##STR89## r.sub.22 r.sub.23 r.sub.24
-54.330 30.242 -217.424 d.sub.22 d.sub.23 d.sub.24 4.646 2.398
1.431 N.sub.13N.sub.14 1.805181.56994 .nu..sub.13.nu..sub.14
25.4348.06 ##STR90## r.sub.25 r.sub.26 r.sub.27 -29.136 42.629
-115.579 d.sub.25 d.sub.26 0.200 4.670 N.sub.15 1.57616 .nu..sub.15
41.42 ______________________________________
TABLE 11 ______________________________________ [ Embodiment 11] f
= 36.0.about.85.0.about.195.0 F.sub.No. = 3.6.about.4.6
______________________________________ ##STR91##
r.sub.1r.sub.2r.sub.3 142.85751.813-486.836 d.sub.1d.sub.2
2.20010.500 N.sub.1N.sub.2 1.805181.51680 .nu..sub.1.nu..sub.2
25.4364.12 ##STR92## r.sub.4r.sub.5 54.368379.701 d.sub.3d.sub.4
0.1506.200 N.sub.3 1.77250 .nu..sub.3 49.77 d.sub.5
0.800.about.20.127.about.33.801 ##STR93## r.sub.6r.sub.7r.sub.8
98.77418.096- 74.406 d.sub.6d.sub.7 1.3005.650 N.sub.4 1.77250
.nu..sub.4 49.77 ##STR94## r.sub.9r.sub.10 -23.75358.480
d.sub.8d.sub.9d.sub.10 3.1001.1000.100 N.sub.5N.sub.6
1.805181.77250 .nu..sub.5.nu..sub.6 25.4349.77 ##STR95##
r.sub.11r.sub.12 32.187219.200 d.sub.11d.sub.12 2.7003.000 N.sub.7
1.75000 .nu..sub.7 25.14 ##STR96## r.sub.13r.sub.14 -25.098-55.939
d.sub.13 1.100 N.sub.8 1.61800 .nu..sub.8 63.45 d.sub.14
26.423.about.14.177.about.1.000 ##STR97## r.sub.15r.sub.16r.sub.17
304.152-52.49648.139 d.sub.15d.sub.16 2.8000.150 N.sub.9 1.51680
.nu..sub.9 64.12 ##STR98## r.sub.18r.sub.19 -44.596-39.182
d.sub.17d.sub.18 4.8000.500 N.sub.10 1.51680 .nu..sub.10 64.12
##STR99## r.sub.20 -758.834 d.sub.19d.sub.20
1.100N.sub.111.80518.nu..sub.1125.4311.300.abo ut.4.219.about.3.722
##STR100## r.sub.21r.sub.22 29.507-33.050 d.sub.21d.sub.22
6.9951.200 N.sub.12N.sub.13 1.603421.85000 .nu..sub.12.nu..sub.13
38.0140.51 ##STR101## r.sub.23r.sub.24r.sub.25 -59.499-73.85024.04
d.sub.23d.sub.24 6.6795.584 N.sub.14 1.85026 .nu..sub.14 32.30
##STR102## r.sub.26r.sub.27 -189.788-36.716
d.sub.25d.sub.26d.sub.27 2.3462.5000.150 N.sub.15 1.51680
.nu..sub.15 64.12 ##STR103## r.sub.28r.sub.29 30.688472.927
d.sub.28 3.500 N.sub.16 1.54072 .nu..sub.16 47.20
______________________________________
TABLE 12 ______________________________________ [ Embodiment 12] f
= 36.0.about.100.0.about.195.0 F.sub.No. = 3.6.about.4.6
______________________________________ ##STR104##
r.sub.1r.sub.2r.sub.3 139.89759.231-698.391 d.sub.1d.sub.2
2.0008.000 N.sub.1N.sub.2 1.846661.61800 .nu..sub.1.nu..sub.2
23.8863.45 ##STR105## r.sub.4r.sub.5 53.334192.210 d.sub.3d.sub.4
0.1004.600 N.sub.3 1.75450 .nu..sub.3 51.57 d.sub.5
1.000.about.24.470.about.34.847 ##STR106## r.sub.6r.sub.7r.sub.8
69.48417.324-71.332 d.sub.6d.sub.7 1.2006.200 N.sub.4 1.77250
.nu..sub.4 49.77 ##STR107## r.sub.9r.sub.10 -24.40259.621
d.sub.8d.sub.9d.sub.10 3.3001.0000.100 N.sub.5N.sub.6
1.750001.75450 .nu..sub.5.nu..sub.6 25.1451.57 ##STR108##
r.sub.11r.sub.12r.sub.13 31.909-134.008152.542
d.sub.11d.sub.12d.sub.13 3.3000.8003.000 N.sub.7N.sub.8
1.750001.74000 .nu..sub.7.nu..sub.8 25.1428.26 ##STR109##
r.sub.14r.sub.15 -25.100-62.615 d.sub.14d.sub.15
1.000N.sub.91.61800.nu..sub.963.4525.941.about .11.902.about.1.500
##STR110## r.sub.16r.sub.17r.sub.18 220.689-51.42848.815
d.sub.16d.sub.17d.sub.18 3.0000.1004.600 N.sub.10 N.sub.11 1.51823
1.51823 .nu..sub.10 .nu..sub.11 58.96 58.96 ##STR111##
r.sub.19r.sub.20r.sub.21 -32.041-32.066-194.356
d.sub.19d.sub.20d.sub.21
0.4001.000N.sub.121.84666.nu..sub.1223.8812.00
0.about.2.570.about.2.595 ##STR112## r.sub.22r.sub.23r.sub.24
52.343-42.545-87.512 d.sub.22d.sub.23d.sub.24 7.0401.35010.730
N.sub.13N.sub.14 1.654461.85000 .nu..sub.13.nu..sub.14 33.8640.51
##STR113## r.sub.25r.sub.26r.sub.27 -190.41531.510-245.549
d.sub.25d.sub.26 3.8413.553 N.sub.15 1.83400 .nu..sub.15 37.05
##STR114## r.sub.28r.sub.29r.sub.30 -42.95842.437-359.602
d.sub.27d.sub.28d.sub.29 5.0500.1003.400 N.sub.16N.sub.17
1.495201.49520 .nu..sub.16.nu..sub.17 79.7479.74
______________________________________
TABLE 13 ______________________________________ [Embodiment 13] f =
36.0.about.100.0.about.195.0 F.sub.No. = 3.6.about.4.6
______________________________________ ##STR115##
r.sub.1r.sub.2r.sub.3 145.22653.37953.273 d.sub.1d.sub.2d.sub.3
2.0000.50011.000 N.sub.1N.sub.2 1.846661.69100 .nu..sub.1.nu..sub.2
23.8854.75 ##STR116## r.sub.4r.sub.5r.sub.6 -1485.30963.508252.056
d.sub.4d.sub.5 0.1005.700 N.sub.3 1.80100 .nu..sub.3 46.54 d.sub.6
0.827.about.23.560.about.31.665 ##STR117## r.sub.7r.sub.8
r.sub.9r.sub.10 106.96720.059-120.95265.839 d.sub.7d.sub.8d.sub.9
1.2006.6000.800 N.sub.4N.sub.5 1.754501.61800 .nu..sub.4.nu..sub.5
51.5763.45 ##STR118## r.sub.11r.sub.12 r.sub.13r.sub.14r.sub.15
30.30395.566 -36.32548.780486.779 d.sub.10d.sub.11
d.sub.12d.sub.13d.sub.14 0.1503.391 4.0750.8002.500 N.sub.6
N.sub.7N.sub.8 1.84666 1.691001.75000 .nu..sub.6 .nu..sub.7.nu..sub
.8 23.88 54.7525.14 d.sub.15 35.955.about.16.185.about.2.000
##STR119## r.sub.16r.sub.17r.sub.18 330.832-52.58549.472
d.sub.16d.sub.17d.sub.18 2.9000.1003.787 N.sub.9N.sub.10
1.516801.53241 .nu..sub.9.nu..sub.10 64.1251.54 ##STR120##
r.sub.19r.sub.20r.sub.21 -71.892-55.226789.764 d.sub.19d.sub.20
1.0001.000 N.sub.11 1.80518 .nu..sub.11 25.43 d.sub.21
17.500.about.3.500.about.1.000 ##STR121## r.sub.22r.sub.23r.sub.24
30.050250.393-630.529 d.sub.22d.sub.23d.sub.24 3.5005.0353.500
N.sub.12N.sub.13 1.582671.80100 .nu..sub.12.nu..sub.13 46.4346.54
##STR122## r.sub.25r.sub.26r.sub.27r.sub.28
30.609-129.507-40.22852.910 d.sub.25d.sub.26d.sub.27
3.6942.4000.100 N.sub.14 1.51823 .nu..sub.14 58.96 ##STR123##
r.sub.29r.sub.30r.sub.31 39.961-38.158-84.115
d.sub.28d.sub.29d.sub.30 1.0005.7001.000 N.sub.15N.sub.16N.sub.17
1.850001.495201.58144 .nu..sub.15.nu..sub.16.nu..su b.17
40.5179.7440.83 ______________________________________
TABLE 14 ______________________________________ [Embodiment 14] f =
36.0.about.100.0.about.195.0 F.sub.No. = 4.1.about.4.6
______________________________________ ##STR124##
r.sub.1r.sub.2r.sub.3r.sub.4 144.73555.241147.18688.687
d.sub.1d.sub.2d.sub.3 2.0006.0000.100 N.sub.1N.sub.2 1.805181.65844
.nu..sub.1.nu..sub.2 25.4350.88 ##STR125## r.sub.5r.sub.6r.sub.7
227.43455.486248.359 d.sub.4d.sub.5d.sub.6 4.0000.1005.600
N.sub.3N.sub.4 1.696801.69680 .nu..sub.3.nu..sub.4 55.4355.43
d.sub.7 1.000.about.23.399.about.30.691 ##STR126## r.sub.8r.sub.9
74.39618.273 d.sub.8d.sub.9 1.2007.000 N.sub.5 1.75450 .nu..sub.5
51.57 ##STR127## r.sub.10r.sub.11 -255.54554.582 d.sub.10d.sub.11
0.8000.150 N.sub.6 1.62135 .nu..sub.6 61.28 ##STR128##
r.sub.12r.sub.13 25.925105.604 d.sub.12d.sub.13 3.3913.200 N.sub.7
1.80518 .nu..sub.7 25.43 ##STR129## r.sub.14r.sub.15 -38.771131.420
d.sub.14 0.800 N.sub.8 1.69680 .nu..sub.8 56.47 d.sub.15
38.844.about.16.991.about.1.500 ##STR130## r.sub.16r.sub.17r.sub.18
398.065-46.96647.832 d.sub.16d.sub.17 3.0000.150 N.sub.9 1.51680
.nu..sub.9 64.12 ##STR131## r.sub.19r.sub.20 -66.685607.888
d.sub.18d.sub.19d.sub.20
4.0001.200N.sub.10N.sub.111.532411.80518.nu..s
ub.10.nu..sub.1151.5425.43 17.500.about.3.500.a bout.1.000
##STR132## r.sub.21r.sub.22r.sub.23 27.210124.473-268.353
d.sub.21d.sub.22 4.0005.000 N.sub.12 1.58144 .nu..sub.12 40.83
##STR133## r.sub.24r.sub.25r.sub.26 28.891-121.206-41.107
d.sub.23d.sub.24d.sub.25 3.2003.0003.000 N.sub.13N.sub.14
1.807411.54072 .nu..sub.13.nu..sub.14 31.5947.22 ##STR134##
r.sub.27r.sub.28r.sub.29 57.65138.827-130.084
d.sub.26d.sub.27d.sub.28 0.2001.2004.800 N.sub.15N.sub.16
1.788311.54072 .nu..sub.15.nu..sub.16 47.3247.22
______________________________________
TABLE 15 ______________________________________ [ Embodiment 15] f
= 35.9.about.70.0.about.145.5 F.sub.No. = 3.6.about.4.6
______________________________________ ##STR135##
r.sub.1r.sub.2r.sub.3 148.29051.813-1263.168 d.sub.1d.sub.2
2.0008.500 N.sub.1N.sub.2 1.805181.61800 .nu..sub.1.nu..sub.2
25.4363.45 ##STR136## r.sub.4r.sub.5 55.317282.255 d.sub.3d.sub.4
0.1505.300 N.sub.3 1.77250 .nu..sub.3 49.77 d.sub.5
0.800.about.15.714.about.28.905 ##STR137## r.sub.6r.sub.7r.sub.8
128.50818.068-98.383 d.sub.6d.sub.7 1.2005.200 N.sub.4 1.77250
.nu..sub.4 49.77 ##STR138## r.sub.9r.sub.10 -24.39069.544
d.sub.8d.sub.9d.sub.10 3.0001.1000.100 N.sub.5N.sub.6
1.750001.75450 .nu..sub.5.nu..sub.6 25.1451.57 ##STR139##
r.sub.11r.sub.12 30.920108.083 d.sub.11d.sub.12 2.2002.600 N.sub.7
1.80518 .nu..sub.7 25.43 ##STR140## r.sub.13r.sub.14 -29.144-92.923
d.sub.13 1.100 N.sub.8 1.62135 .nu..sub.8 61.28 d.sub.14
20.356.about.10.888.about.1.000 ##STR141##
r.sub.15r.sub.16r.sub.17r.sub.18 97.931-59.86260.330-40.504
d.sub.15d.sub.16d.sub.17 3.0000.1424.000 N.sub.9N.sub.10
1.516801.51680 .nu..sub.9.nu..sub.10 64.1264.12 ##STR142##
r.sub.19r.sub.20 -33.013-171.775 d.sub.18d.sub.19d.sub.20
1.0001.017 N.sub.11 1.805187.nu..sub.1125.43 1
1.300.about.5.854.about.2.552 ##STR143## r.sub.21r.sub.22
32.419-59.807 d.sub.21d.sub.22 6.0846.981 N.sub.12 1.60323
.nu..sub.12 42.30 ##STR144## r.sub.23r.sub.24r.sub.25
-40.13132.306-236.076 d.sub.23d.sub.24d.sub.25 2.7031.9333.052
N.sub.13N.sub.14 1.834001.51680 .nu..sub.13.nu..sub.14 37.0564.12
##STR145## r.sub.26r.sub.27r.sub.28 -31.09549.978-96.905
d.sub.26d.sub.27 0.1423.500 N.sub.15 1.51680 .nu..sub.15 64.12
______________________________________
TABLE 16 ______________________________________ [ Embodiment 16] f
= 35.9.about.70.0.about.145.0 F.sub.No. = 3.6.about.4.6
______________________________________ ##STR146##
r.sub.1r.sub.2r.sub.3 148.29054.9457330.300 d.sub.1d.sub.2
2.0007.000 N.sub.1N.sub.2 1.805181.61800 .nu..sub.1.nu..sub.2
25.4363.45 ##STR147## r.sub.4r.sub.5 57.500270.330 d.sub.3d.sub.4
0.1505.000 N.sub.3 1.77250 .nu..sub.3 49.77 d.sub.5
0.800.about.16.796.about.31.265 ##STR148## r.sub.6r.sub.7r.sub.8
144.20917.446-82.399 d.sub.6d.sub.7 1.2005.800 N.sub.4 1.77250
.nu..sub.4 49.77 ##STR149## r.sub.9r.sub.10 -28.57171.180
d.sub.8d.sub.9d.sub.10 2.8001.1000.100 N.sub.5N.sub.6
1.805181.77250 .nu..sub.5.nu..sub.6 25.4349.77 ##STR150##
r.sub.11r.sub.12 31.160105.637 d.sub.11d.sub.12 2.2002.900 N.sub.7
1.80518 .nu..sub.7 25.43 ##STR151## r.sub.13r.sub.14 -29.791-59.361
d.sub.13 1.100 N.sub.8 1.51680 .nu..sub.8 64.12 d.sub.14
22.433.about.11.598.about.1.000 ##STR152## r.sub.15r.sub.16r.sub.17
73.655-74.72346.590 d.sub.15d.sub.16 2.5000.142 N.sub.9 1.52133
.nu..sub.9 51.06 ##STR153## r.sub.18r.sub.19 -53.564-44.323
d.sub.17d.sub.18 3.5000.400 N.sub.10 1.51680 .nu..sub.10 64.12
##STR154## r.sub.20 -578.288 d.sub.19d.sub.20
1.200N.sub.111.80518.nu..sub.1125.4311.000.abo ut.5.839.about.1.968
##STR155## r.sub.21r.sub.22 28.336-78.124 d.sub.21d.sub.22
4.8895.640 N.sub.12 1.58267 .nu..sub.12 46.43 ##STR156##
r.sub.23r.sub.24r.sub.25 -46.29327.35111270.140 d.sub.23d.sub.24
2.6372.142 N.sub.13 1.83400 .nu..sub.13 37.05 ##STR157##
r.sub.26r.sub.27r.sub.28 -30.07751.849-688.861
d.sub.25d.sub.26d.sub.27 3.0520.1423.000 N.sub.14N.sub.15
10516801.51680 .nu..sub.14 .nu..sub.15 64.1264.12
______________________________________
TABLE 17 ______________________________________ [Embodiment 17] f =
35.9.about.70.0.about.131.5 F.sub.No. = 3.6.about.4.6
______________________________________ ##STR158##
r.sub.1r.sub.2r.sub.3 148.29050.000-1116.918 d.sub.1d.sub.2
2.0008.400 N.sub.1N.sub.2 1.805181.61800 .nu..sub.1.nu..sub.2
25.4363.45 ##STR159## r.sub.4r.sub.5 49.222264.280 d.sub.3d.sub.4
0.1505.800 N.sub.3 1.77250 .nu..sub.3 49.77 d.sub.5
0.800.about.14.519.about.24.858 ##STR160## r.sub.6r.sub.7r.sub.8
251.25616.424-77.830 d.sub.6d.sub.7 1.2005.400 N.sub.4 1.77250
.nu..sub.4 49.77 ##STR161## r.sub.9r.sub.10 -24.39066.861
d.sub.8d.sub.9d.sub.10 2.8001.1000.100 N.sub.5N.sub.6
1.805181.77250 .nu..sub.5.nu..sub.6 25.4349.77 ##STR162##
r.sub.11r.sub.12 29.32399.974 d.sub.11d.sub.12 2.2002.700 N.sub.7
1.80518 .nu..sub.7 25.43 ##STR163## r.sub.13r.sub.14 -29.114-65.390
d.sub.13 1.100 N.sub.8 1.51680 .nu..sub.8 64.12 d.sub.14
19.357.about.9.960.about.1.000 ##STR164## r.sub.15r.sub.16r.sub.17
84.052-61.03950.927 d.sub.15d.sub.16 2.5000.142 N.sub.9 1.51680
.nu..sub.9 64.12 ##STR165## r.sub.18r.sub.19 -48.381-40.239
d.sub.17d.sub.18 3.5000.400 N.sub.10 1.51680 .nu..sub.10 64.12
##STR166## r.sub.20 -277.612 d.sub.19d.sub.20
1.200N.sub.111.80518.nu..sub.1125.439.500.abou t.5.178.about.3.789
##STR167## r.sub.21r.sub.22 28.906-75.104 d.sub.21d.sub.22
6.0256.844 N.sub.12 1.58267 .nu..sub.12 46.43 ##STR168##
r.sub.23r.sub.24r.sub.25 -41.03328.470-556.538 d.sub.23d.sub.24
2.6371.933 N.sub.13 1.83400 .nu..sub.13 37.05 ##STR169##
r.sub.26r.sub.27r.sub.28 -31.91549.949-102.528
d.sub.25d.sub.26d.sub.26 3.0520.1423.500 N.sub.14N.sub.15
1.516801.51680 .nu..sub.14.nu..sub.15 64.1264.12
______________________________________
In the above embodiments, the eighth to seventeenth embodiments
relate to relatively greater zoom ranges. With respect to these
embodiments, condition (3) is limited as follows:
Further, the eleventh to seventeenth embodiments show especially
wide zoom ranges reaching a considerate telephoto field angle. For
these embodiments, the present invention provides the following
condition:
wherein: f.sub.T represents the longest focal length of the whole
lens system.
Condition (9) is for providing a zoom lens system with a high zoom
ratio and well corrected aberrations. If the upper limit is
violated, any zoom lens system with a high zoom ratio such as about
3 to 6 and a high optical performance would not be attained unless
the compactness of the lens system is abandoned. On the other hand,
if the lower limit is violated, the desirable balance in correcting
various aberrations, especially between the corrections of
spherical aberration and coma, would be hardly possible and the
correction of the lateral chromatic aberration would also be
difficult.
In the drawings, the solid lines below the cross sectional views of
the lens systems roughly show the movement of the lens groups upon
zooming toward the longest focal length side, while the straight
broken lines represent that the corresponding lens groups are left
stationary upon zooming. Most of the embodiments belong to a type
in which the first positive lens group (I) is moved toward the
object side, the second negative lens group (II) is moved toward
the image side or left stationary and the third positive lens group
(III) is moved toward the object side, upon zooming from the
shortest to the longest focal length of the whole lens system, the
third positive lens group (III) being divided into two positive
subunits (III-1 and III-2) for reducing the air space therebetween
in accordance with the increase of the focal length of the whole
lens system. These type of embodiments, the object side positive
subunit (III-1) in the third positive lens group (III) consists of
a pair of positive lens elements and a negative lens element, the
two of which may be cemented to form a doublet. Further, the image
side positive subunit (III-2) of the third positive lens group
(III) in the eighth to seventeenth embodiments is basically of a
triplet type with a positive-negative-positive power
distribution.
As is apparent from the above disclosure, the present invention
provides a compact zoom lens system of a high zoom ratio ranging to
a wide field angle with a high optical performance. For example, in
the ninth and tenth embodiments, a filter of diameter, 55 .phi. can
be attached thereto.
As can be readily appreciated, it is possible to deviate from the
above embodiments of the present invention and, as will be readily
understood by those skilled in the optical art, the invention is
capable of many modifications and improvements within the scope and
spirit thereof. Accordingly, it will be understood that the
invention is not to be limited by these specific embodiments, but
only by the scope and spirit of the appended claims.
* * * * *